stem cells as cancer therapy?

One last stem cell related blog and I promise, I’ll move on to a new topic.

There have been some interesting articles in the science literature about the potential use of stem cells to treat cancer. This is based on basic research and is not yet used in any clinical trials or ready for prime time. It is an interesting idea that MAY show promise as a therapy someday but is NOT there yet. Therefore, I am not advocating that it should be sought out as a therapy now or that if this does exist anywhere it will be beneficial. Time will tell as more research is conducted if it is a good therapy or if some other therapy will come of out of this research.

Mesenchymal stem cells are cells found in the bone marrow. Actually, there are two types of bone morrow derived stem cells, hematopoetic (that go on to become white blood cells) and mesenchymal (that can differentiate into many cell types and are involved in wound/tissue repair). It also turns out that mesenchymal stem cells (MSC), because of their role in wound repair and tissue regeneration, migrate to cancer tumor sites. The current understanding is that tumor cells release agents called chemokines that attract MSCs to the site. The role of these MSCs within tumors is still largely unclear but it is thought that they may contribute to supporting tumor growth. Interestingly, scientists have been looking at how to use this migration capacity of MSCs to turn these cells into cells that deliver some form of therapy (aka a vector for cancer therapy). Basically, MSCs can be engineered to express a gene that will kill the tumor cells. For example, MSCs can be made to express the interferon beta protein and then used to target to melanoma tumors. Interferon beta has been shown to inhibit tumor growth by causing cells to stop growing and die.

The advantage of using MSCs instead of just injecting a drug or ingesting a pill is that MSCs could be better at targeting to a tumor site and reducing the unintended side effects by affecting non-tumor cells. This would be especially beneficial for tumors that are hard to access such a solid tumors in the breast, etc...

As I said at the beginning of this piece, this is a test of a theory that is being investigated. It is a very attractive idea, to use cells that preferentially go to tumor sites as a method to deliver therapy. There is still a lot that isn’t known yet, like will the MSCs themselves promote tumor growth? For now, it is a novel way to deliver therapy directly to the tumor site. Hopefully, this research will continue to progress.

stem cells?!

Thank you to the submitter of this week’s topic: in light of my last blog, what about stem cells and why all the controversy? This is a fascinating topic and parts are hotly debated. Stem cells come in a several flavors. There are adult stem cells, hematopoetic (white cells in the blood) stem cells, embryonic stem cells (ES) and the most recently identified inducible pluripotent stem cells (iPS). These iPS cells are artificially derived cells that are created from adult cells by forcing the expression of a particular set of genes.

A common characteristic of all stem cells is that they are all slow growing cells that are “immature”. Given the appropriate signals, they can be coerced to develop into any cell in the body. The most easily manipulated are the embryonic stem cells, but these are highly controversial since they come from embryos (usually from ones that are donated after in vitro fertilization techniques. They are the frozen embryos that are not implanted or used in that process). Use of ES cells opens the whole debate about when life begins and it is morally right to use embryos in this manner, even if their fate would be to be frozen permanently? That is a discussion for another day.

The overall goal with stem cells is to isolate them from various sources, including by the way from fat cells in our bodies (I’d donate!), and stimulate them to become whatever cell type is necessary. Have a bad heart? Take stem cells and stimulate them to become heart cells that can be introduced into the ailing heart and “cure” it. In reality, this isn’t close to happening. Stem cells are being studied and understood more and more each day. The field has moved forward quite rapidly and hopefully will be widely used in clinical settings some day. For now, it is too soon to really use them in meaningful clinical ways, especially iPS cells. As more is understood about how these cells grow and (more importantly) how they don’t keep growing, the better their use will be as therapy. Until then, they are being used in cell culture models to understand more about how cells work and develop. A useful and informative by-product to these studies is that this information can be used by non-stem cell researchers to understand how those cells work as well. In other words, the research isn’t limited to just stem cells alone.